1. Field of the Invention
This invention relates to an axle suspension system and more particularly to a drive axle suspension system utilizing a parallelogram-type suspension system. More particularly, the axle suspension system of this invention combines the functions of upper control arms and a stabilizer bar.
2. Description of the Related Art
In many conventional rear drive axle suspension systems for trucks, the opposite ends of the rear drive axle are secured to the frame members of the truck by leaf spring suspension systems. Although the leaf spring suspension systems have functioned well for many years, it is sometimes desirable to replace the leaf springs with air spring to enhance the load carrying characteristics of the suspension system.
One prior art axle suspension system is known as a parallelogram-type axle suspension system wherein a pair of upper and lower control arms are provided beneath each of the frame members of the truck with the forward ends of the control arms being pivotally secured to mounting brackets and with the rearward ends of the control arms being secured to axle supports. Although the parallelogram-type axle suspension systems have met with considerable success, a separate sway bar or stabilizer bar is sometimes required to control roll or sway movements. The need for a separate stabilizer bar involves additional mounting problems and expense.
In the instant invention, a conventional leaf spring suspension system is replaced with an air spring suspension system. First, the leaf springs are removed from the first and second frame members of the truck and are removed from the axle. First and second mounting brackets are secured to the first and second frame members and extend downwardly therefrom. First and second lower control arms are pivotally secured at their forward ends to the first and second mounting brackets, respectively, and extend rearwardly therefrom. The first and second lower control arms are pivotally secured at their rearward ends to first and second axle supports, respectively. The first and second axle supports support the axle and wheel assembly thereon in a conventional manner. A stabilizer bar assembly is provided including an elongated, generally transversely extending base portion having first and second generally forwardly extending end portions at the opposite ends thereof. The base portion of the stabilizer bar assembly is pivotally secured to each of the first and second axle supports. The forward ends of the first and second generally forwardly extending end portions of the stabilizer bar assembly are pivotally secured to the first and second mounting brackets above the lower control arms. The stabilizer bar assembly combines the functions of upper control arms and a stabilizer or sway bar. It should be noted that the stabilizer bar assembly could combine the functions of the lower control arms with independent upper control arms.
It is therefore a principal object of the invention to provide an improved axle suspension system.
Still another object of the invention is to provide an axle suspension system of the parallelogram-type wherein the functions of either the upper or lower control arms and a stabilizer bar are combined into one.
These and other objects will be apparent to those skilled in the art.